Kitchen ventilator exhaust hoods have long been provided for the purpose of exhausting steam, smoke, heat and effluent particulates such as grease (e.g., generally referred to as the thermal plume) that are produced by cooking appliances in the commercial cooking environment. A variety of exhaust hood configurations are known. A typical hood system configuration is depicted in FIG. 1, where an apron 10 of the hood 12 forces the buoyancy driven exhaust flows to change direction resulting in lateral flows proximate the filter aperture such that increased exhaust airflow rates are required to maintain capture and containment. The filter aperture 14 and filter unit 16 are angled at approximately 45 degrees or greater to vertical, and the thermal plume and replacement air are shown respectively by flows 18 and 20. Notably, the replacement air flow includes a significant component that travels between the rear side of the commercial cooking appliances 22 (e.g., ranges, broilers, frying apparatus etc.) and the building wall structure 24. In order to assure the capture of substantially all of the thermal plume, existing hood systems typically draw off and expel an undesirably large volume of air.
Accordingly, in view of the ever increasing demand and importance of energy efficiency, improved systems are sought to capture and contain substantially all of the thermal plume while reducing the volume of air drawn through the hood.